Method of producing lubricating oil



Jan. l2, 1937. R. c. osTERsTRoM I METHOD OF PRODUCING' LUBRICATING OIL Filed NOV. 19, 1931 Kmsmkm @GW --1 /l atented Jan. 12, 1937 TED STATES PATENT OFFICE Rudolph C. Osterstrom, Chicago, Ill., assigner to The Pure Oil Company, Chicago, Ill., a corporation of Ohio Application November 19, 1931, Serial No. 576,127

1 Claim.

This invention relates to an improved method of treating hydrocarbon oils and, more particularly, to the treatment of unsaturated hydrocarbon distillates obtained from high temperature vapor phase cracking processes.

I have found that in the treatment of cracked gasoline, particularly of the type derived from vapor phase cracking, any residue, after the material with a gasoline boiling range has been extracted, contains appreciable quantities of highly satisfactory lubricating oils with an unusually low pour test. It has been observed that when distilled, preferably in vacuum, the pitch-like substance in the polymers formed as a result of treating vapor phase cracked gasoline, can be distilled out as a residue and the vaporizable or overhead ycompound separated into fractions, some of which having marked value as lubricating oils. Those products or fractions selected as lubricants can be further treated in a desired manner with sulfuric acid followed by neutralization and filtration, straight filtration by the percolation method or by contact with an adsorbent to produce the nished commercial lubricant.

It is another object of my invention to provide an improved lubricating oil which may be blended with lubricating oils known as neutrals or partially dewaxed hydrocarbon oils for the purpose of producing a blended oil having a low pour point without resorting to the usual expedient of substantially completely dewaxing such neutrals before they can be used as lubricating oils under cold climatic conditions. In this respect the synthetic lubricating oil fraction, produced in accordance with my invention, functions as an inhibitor to wax crystallization in partially dewaxed oil, thus lowering the pour test.

The invention will be further described in ccnnection with the accompanying drawing which illustrates, diagrammatically and conventionally, one form of apparatus adapted for carrying out the process of the invention. The particular apparatus shown has been set forth merely for purposes of illustration and not by way of limitation. In my previous application, Serial No. 517,897 led February 24, 1931, I have described a process for eiecting the separation by fractionation of aromatic type lubricating oils from the products of vapor phase cracking, wherein high boiling oils are subjected to cracking temperatures of the order of from 1000 F. to 1250 F. to produce low boiling oil, usable as motor fuel distillates and at the same time treating residual oils, formed as a result of such cracking operation,

and which possess a boiling range higher than that of gasoline, to heat treatment and purification for the purpose of obtaining an aromatic lubricating oil of a wax-free heat resisting character. I have now found that in addition to the high boiling residual oils, produced as a result of vapor phase cracking, I can utilize in the production of a lubricating oil high boiling compounds produced through the treatment of vapor phase cracked distillates to remove gums and resinous compounds or other objectionable compounds or impurities. The present invention is addressed, therefore, specifically to the use of the high boiling products separated from an unsaturated cracked distillate for the purpose of producing a new and highly efficient lubricating oil fraction which may be used either directly as a lubricating oil or in many instances as a blend for improving certain of the characteristics of lubri- I eating oils produced by other processes.

As shown in the accompanying drawing, the numeral I designates a tank or other receiver which is adapted to contain a body of vapor phase cracked distillate. These distillates, as is well known, are characterized by a high percentage of unsaturated compounds, which compounds if permitted toremain in the distillate, especially the more highly reactive compounds, such as the diolenes, readily oxidize upon exposure to light and air and produce resinous like bodies which are objectionable in a motor fuel spirit. To effect the removal of these objectionable compounds by selective polymerization, that is, the removal of those compounds which produce gum-forming and color-imparting bodies in the distillate, the latter is passed from the tank I and is forced by means of a pump 2 through a pipe line 3 which leads to a heating coil 4 located in a polymerizing still 5. In this still, the cracked distillate is heated to a temperature of the order of approximately 500 F. to 600 F. while maintained under super-atmospheric pressure sufficiently high to keep the distillate in substantially the liquid phase. From the coil 4, the oil is passed Without appreciable reduction in pressure through an inclined reaction drum 6v located exteriorly of the still 5. Inthe lower portion of the drum 6 there is disposed a body of a nely divided solid adsorbent, which is indicatedby the numeral l. The oil is forced through the material l, which may be in the form of fullers earth, silica gel, charcoal and the like, and is then passed through a pipe line 8 leading to a separating tower 9. Inthe line 8, there is arranged a pressure reducing valve I Il so that when the products of the polymerizing process are discharged into the tower 9, the lighter low boiling compounds vaporize and pass overhead through a pipe line II. These low boiling compounds, due to the polymerizlng action, are substantially entirely free from those objectionable unsaturated compounds which tend to form gums or resins, and the distillate passing through the line II may be condensed as at I2 and received within a storage tank I3 as a nished motor fuel spirit. While this distillate contains a relatively largeamount of unsaturated compound and is Ahighly effective as an anti-detonating motor fuel, yet as stated, it is substantially devoid of the undesirable color producing and gum forming bodies. Due to the heating of the oil in the coil 4 under the conditions of pressure and temperature described and the passage of this oil through the bed 1 composed of the solid nely divided adsorbent, those reactive 1 compounds are polymerized into compounds having a higher boiling range, than the oils charged from the tank I to the still 5. These polymerized high boiling oils accumulate as liquids in the bottom of the separator 9 and may be withdrawn ,by means of a valved pipe line I4 which leads to a re-run still I5.

In the still I5, the residual polymerized oil, ob-

tained as a result of the selective polymerizing of cracked low boiling unsaturated oil, are subject to redistillation preferably under vacuum conditions although ordinary pressures may be employed. Inthe still I5 the polymerized oils are subjected to a sucient degree of heat to vaporize, without any substantial cracking, the lower boiling compounds therein contained and, usually the operation in the still I5 takes place .without the aid of a catalyst. I preferably use a vacuum or sub-atmospheric pressures in the still I5 to facilitate vaporization of the lower boiling compound at temperatures below the critical cracking temperatures of these complex hydrocarbon bodies constituting the residual products -heated in said still.

The products vaporized in the still I5 pass. to a fractionating tower I6 and are therein separated into a plurality of fractionated cuts,` as

indicated by the lines I1, I'Ia, I1b, I1c and I1d, which cuts differ from each other by virtue of their respective boiling ranges. Any suitable means, pump |16, may be employed for maintaining a desired vacuum or sub-atmospheric pressures in the tank I5. Usually, distillation` in the still I5 is carried on to cause the pitch-like substances in the polymers to be distilled out as a residue, while the lower boiling overhead products are passed from the top of the still I5 by way of a pipe line I8 to the fractionation tower I6. 'I'he pitch-like products formed as a result of this redistillation may be removed from the still I5 by way of a valved outlet line I9. The

lines I1 to I1d may be provided with condensing coils or heat exchangers for cooling the oils durf ing their passage to receiving tanks 20.

The oils received within the tanks 20 and particularly the lighter oils which pass through the lines I1 and Ila possess high value as lubricating oils. These oils may be treated in any desired conventional manner to remove impurities, and in this instance I have shown each of the tanks 20 as equipped with a valved outlet which may be either simultaneously or selectively operated to permit of oil flow through a pipe line 2I. Sulfuric acid obtained from a tank 22 may be introduced into the oils owing through the line 2| by means of a valved branch23. The oils mingled with regulated quantities of sulfuric acid are then passed under pressure of a pump 24 through an orifice mixer 25, and thence delivered to an agitator or settling tank 26. The acid treated oil is withdrawn from the bottom of the tank 26 and passed through -a line 21, a neutralizing alkali, usually caustic soda, being intro-V duced into the line 21 from a tank 28. This mixture is then passed through a second orice mixer 29 under the pressure of a pump 30, and

is then delivered to a second agitator or settling tank 3|. From the bottom of the tank 3l, the purified oil is withdrawn by way of a line 32 and passed through a container 33 in which is positioned a body of fullers earth, whereby to remove nal traces of impurities present in the oil. Following passage through the container 33, the treated purifled lubricating oil is then transmitted to a storage tank or receptacle 34. Waste products or sludge may be removed from the bottom ofthe tanks 26 and 3I by way of outlet lines suitably valved. I

While I have illustrated and described in detail one method for effecting the selective polymerization of cracked unsaturated low boiling oils for the purpose of removing objectionable gum forming and color imparting bodies therefrom, nevertheless it will be understood by those skilled in the art that I do not limit myself to purification as the percolation method, or the treatment of such oils with sulfur dioxide. Likewise, the still I5 may be in the form of a tube `still and operated in vacua after the disclosures contained in the patent to I-Iarnsberger No. 1,666,597, granted April 1'7, 1928, my invention residing primarily in a process for effecting the separation and treatment of polymer containing residual oils formed as a result of the treatment of cracked low boiling unsaturated oils to remove gum, to produce a new synthetic lubricating oil, with or without the aid of a catalyst while the oil is undergoing redistillation in a heating unit corresponding to the still 15. I have found that the lubricating oil removed, for example, from the tank 34, may be used either directly as a lubricant or, more preferably, may be blended with a partially dewaxed neutral to lower the pour test of said neutral oil by a simple blending operation. Apparently, my improved synthetic lubricating oil functions when blendedin such a blend as an inhibitor to wax crystallization so that a neutral oil having a pour test of, for example, 32 F. when properly blended with the lubricating oil produced in accordance with the present invention, will possess a pour pointrv approximately of 0 F.

What is claimed is:

A process for treating `unsaturated hydrocarbon distillate produced by vapor phase cracking, in order to prepare therefrom nished motor-fuel and lubricating oil, which comprises contacting said distillate with an adsorptive polymerizing catalyst at temperatures of the order of 500600 F. under pressures suiliciently high to keep distillate in the liquid phase in order to selectively polymerize the color-imparting and gum-forming constituents contained therein, separating from the polymers, hydrocarbons boiling within the motor fuel range. said hydrocarbons containing a large percentage of unsaturated compounds but being substantially devoid of colorproducing and gum-forming bodies, distilling the polymers under sub-atmospheric pressure below cracking temperature to remove therefrom pitchlike substances as a residue, condensing a viscous l distillate fraction. subjecting said fraction to rening with sulfuric acid in order to remove impurities therefrom, and neutralizing the acid treated distilnte.

RUDOLPH C. OSTERSTROM. 

